A4988 Stepper Motor Driver Carrier with male header pins installed, so no soldering is required to use it with an appropriate 16-pin socket or solderless breadboard. Pololu 2980

DRV8825 Stepper Motor Driver Carrier with male header pins installed, so no soldering is required to use it with an appropriate 16-pin socket or solderless breadboard. Pololu 2982

Copper alloy traveling nut intended for use with Tr8×8(P2) threaded rods and features a mounting flange with four holes threaded for M3 screws. Pololu 2688

The A-Star 32U4 Prime SV is a programmable board based on Atmel’s ATmega32U4 microcontroller and arranged in the common Arduino form factor. The A-Star Prime offers many additional features and improvements over competing products. Pololu 3115

A small, low-power motor with a 5:1 metal gear, 6 V operating voltage, 0.02 A to 0.36 A power consumption, 2500 RPM speed and a maximum torque of 0.05 kg * cm. Pololu 1100

10:1 Micro Metal Gearmotor

Pololu - 2511

These 17 mm long aluminum adapters convert a 3 mm diameter shaft to a 12 mm hex shaft that compatible with many common hobby RC wheels. The set includes two adapters, two M4 screws for securing wheels to the adapters, four M3 set screws for securing the adapters to motor shafts, and one 1.5 mm Allen wrench for use with the set screws.

A set of adapters (adapter) from the popular 4 mm to 12 mm motor shaft, wheel holders from RC models. Pololu 2684

The Pololu A-Star 32U4 Prime is a general-purpose programmable board based on Atmel’s ATmega32U4 AVR microcontroller and arranged in the common Arduino form factor exemplified by the Uno R3 and Leonardo. Pololu 3107

The module protects the load against reverse polarity to -60 V, but does not block reverse current, which is desirable in applications such as motor control. It uses the LM74500-Q1 controller and a MOSFET transistor. Thanks to its low impedance (1.5 mΩ), it supports currents up to 25 A continuous and 50 A transient, providing reliable protection and the possibility of easy assembly. Pololu 5387

Pololu - 2737

The Pololu Pushbutton Power Switches are sophisticated power control alternatives to bulky mechanical switches. The main function is pushbutton-based latching power control, where one push turns on power and another push turns it off.

Great for learning the basics of gears and linkages, this Tamiya kit contains all the parts necessary to make a remote controlled crawler that picks up ping pong balls. Pololu - 2389

This compact expansion board plugs directly into the GPIO header on a Raspberry Pi B+, A+, or Pi 2 and provides an easy and low-cost solution for driving a pair of small brushed DC motors. Pololu 2753

Pololu 6V Step-Up Voltage Regulator U3V50F6

This gearmotor is a miniature high-power, 12 V brushed DC motor with long-life carbon brushes and a 100.37:1 metal gearbox. It has a cross section of 10 × 12 mm, and the D-shaped gearbox output shaft is 9 mm long and 3 mm in diameter. This version also has a 4.5 × 1 mm extended motor shaft.

Key specs at 12 V: 320 RPM and 100 mA with no load, 30 oz-in (2.2 kg-cm) and 0.8 A at stall.

Small, plastic support ball, 1" diameter (25.4 mm). It can be used as a support element in a two-wheeled mobile robot. Pololu 952

This gearmotor is a miniature low-power, 6 V brushed DC motor with a 75.81:1 metal gearbox. It has a cross section of 10 × 12 mm, and the D-shaped gearbox output shaft is 9 mm long and 3 mm in diameter. This version also has a 4.5 × 1 mm extended motor shaft.

Pololu 4-Channel RC Servo Multiplexer (Assembled)